[PATCH v3 5/8] tools/init-dom0less: Use introduced to determine no-enhanced

[Jason Andryuk <jason.andryuk@amd.com>]

A hardware+xenstore domain will not be able to read HVM params, and
init-dom0less reads HVM_PARAM_STORE_EVTCHN to determine whether or not
a domain has xenstore.

xenstored had a similar issue, and it just tries to map a domain's
reserved grant, GNTTAB_RESERVED_XENSTORE, to see if it is accessible.
If successful, xenstored introduces the domain.  Use the existing
introduced state to determine if init-dom0less should try and read the
param.  If already introduced, initialization (and reading the
HVM_PARAM) is skipped.

This allows for running init-dom0less from a xenstored+hardware domain.
It relies on the local socket xenstore connections being considered
privileged.

oxenstored has not been updated, so the exist code remains for backwards
compatibility.

Signed-off-by: Jason Andryuk <jason.andryuk@amd.com>
---
v3:
New
---
 tools/helpers/init-dom0less.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/helpers/init-dom0less.c b/tools/helpers/init-dom0less.c
index eb793c7aab..a4de40aeac 100644
--- a/tools/helpers/init-dom0less.c
+++ b/tools/helpers/init-dom0less.c
@@ -309,16 +309,20 @@ static int configure_xenstore(libxl_dominfo *info,
 
 static int init_domain(libxl_dominfo *info)
 {
-    uint64_t xenstore_evtchn, xenstore_pfn = 0;
+    uint64_t xenstore_evtchn = 0, xenstore_pfn = 0;
+    bool introduced;
     libxl_uuid uuid;
     int rc;
 
-    rc = configure_xenstore(info, &xenstore_evtchn, &xenstore_pfn);
-    if (rc)
-        return rc;
+    introduced = xs_is_domain_introduced(xsh, info->domid);
+    if (!introduced) {
+        rc = configure_xenstore(info, &xenstore_evtchn, &xenstore_pfn);
+        if (rc)
+            return rc;
 
-    if (xenstore_evtchn == 0) {
-        return 0;
+        if (xenstore_evtchn == 0) {
+            return 0;
+        }
     }
 
     libxl_uuid_generate(&uuid);
@@ -332,7 +336,7 @@ static int init_domain(libxl_dominfo *info)
     if (rc)
         err(1, "writing to xenstore");
 
-    if (!xs_is_domain_introduced(xsh, info->domid)) {
+    if (!introduced) {
         rc = xs_introduce_domain(xsh, info->domid, xenstore_pfn,
                                  xenstore_evtchn);
         if (!rc)
-- 
2.50.1